1. Field of the Invention
This invention relates to extraction cleaning. In one of its aspects, the invention relates to extraction cleaning with enhanced cleaning performance. In another of its aspects, the invention relates to an extraction cleaning machine wherein the dwell time for cleaning fluid applied to a surface to be cleaned is constant regardless of the direction of movement of the cleaning machine. In another of its aspects, the invention relates to a method for cleaning a carpet or other floor surface wherein a cleaning module with a suction nozzle is moved forwardly and rearwardly along the surface to be cleaned and cleaning fluid is applied to the surface after suction is applied to the surface to equalize the dwell time of the cleaning fluid regardless of the direction of movement of the cleaning module along the surface to be cleaned.
2. Description of the Related Art
Extraction cleaning machines have been used for removing dirt from surfaces such as carpeting and hard surface floors. The extraction cleaning machines can be in the form of a canister-type unit, as disclosed in U.S. Pat. No. 5,237,720 to Blase et al., or an upright unit, as disclosed in U.S. Pat. No. 6,131,237 to Kasper et al.
Either type of unit contains a fluid delivery system for depositing a quantity of cleaning solution on the surface through a spray dispenser assembly. The cleaning solution dissolves the dirt, removes the dirt from the surface to be cleaned, and places the dirt in suspension, which aids in the vacuum removal of the dirt from the surface. After a period of time, the cleaning solution is removed through a vacuum process. The longer the cleaning solution remains on the surface, the more effective the cleaning solution is in cleaning the surface.
Conventional extraction cleaning machines have a spray dispenser assembly which is typically adjacent to and to the rear of the suction nozzle. As the extraction cleaning machine is moved in a forward direction, the cleaning fluid will be deposited on the surface to be cleaned behind the suction nozzle, leaving a wetted surface behind it. When the extraction cleaning machine is moved rearwardly, the suction nozzle trails the spray dispenser and removes the cleaning fluid almost as soon as it is applied to the surface. Consequently, the cleaning solution has a different dwell time on the surface between the forward and rearward stroke of the machine. Further, the surface is scrubbed with a brush in the forward direction after the cleaning solution is deposited and is scrubbed with a brush before application of the cleaning solution on the rearward stroke. Accordingly, the cleaning fluid may not remain on the surface to be cleaned a sufficient time to most effectively clean the surface on the rearward stroke of the machine.
U.S. Pat. No. 4,014,067 to Bates discloses a carpet cleaner having a pair of spray dispensers on either side of a scrubbing brush and behind the suction nozzle.
U.S. Pat. No. 6,681,442 to Coates et al., issued Jan. 27, 2004, discloses an extractor having a spray dispenser for depositing different liquids to a surface wherein the liquid delivery is controlled by the direction of movement of the extractor.